Catalytic preparation of polyketone from carbon monoxide and olefin

ABSTRACT

Copolymers of ethylene and CO(polyketones) are produced by copolymerization in the presence of a catalyst comprising palladium, cobalt or nickel, a bidentate phosphine ligand and a non-coordinating anion, e.g., derived from p-toluene sulfonic acid.

This is a continuation of application Ser. No. 596,788, filed Apr. 4,1984, now abandoned.

FIELD OF THE INVENTION

The invention relates to a process for the preparation of polyketones bypolymerizing a mixture of CO and an alkenically unsaturated hydrocarbonin the presence of a Group VIII metal catalyst containing ligands, inwhich hydrocarbon groups occur that are bonded to an element from groupVb.

BACKGROUND OF THE INVENTION

A process for preparing polyketones from carbon monoxide and ethylene isdisclosed in U.S. Pat. Nos. 3,689,460 and 3,694,412. The catalystsdescribed therein are complexes of a palladium chloride orπ-allylpalladium chloride and two trihydrocarbylphosphine monodentateligands, e.g., triphenylphosphine. However, the polymer yields remainrelatively small, viz. less than 35 g/g Pd/hour at a pressure of 70 bar.Another process for preparing polyketones is discussed by Sen and Lai inthe article entitled "Novel Palladium (II)-Catalyzed Copolymerization ofCarbon Monoxide with Olefins", J. Am. Chem. Soc. 1982, 104, 3520-3522.

A new process for preparing polyketones in high yields is disclosed.

SUMMARY OF THE INVENTION

The present invention concerns a process for the preparation ofpolyketones by polymerizing a mixture of CO and an alkenicallyunsaturated hydrocarbon in the presence of a Group VIII metal catalystcontaining ligands, in which hydrocarbon groups occur that are bonded toan element from group Vb, characterized in that, as catalyst, a complexcompound is used that is obtained by reacting a palladium, cobalt ornickel compound, a bidentate ligand of the general formula R¹ R²--M--R--M--R³ R⁴, in which M represents phosphorus, arsenic or antimony,R¹, R², R³ and R⁴ are identical or different hydrocarbon groups, and Rrepresents a divalent organic bridging group having at least two carbonatoms in the bridge, none of these carbon atoms carrying substituentsthat may cause steric hindrance, and an anion of an acid with a pKa ofless than 2, provided said acid is neither a hydrohalogenic acid nor acarboxylic acid.

DETAILED DESCRIPTION OF THE INVENTION

The anions used in the process according to the invention are preferablynon-coordinating anions, by which is meant that little or no covalentinteraction takes place between the palladium and the anion (cf. GB-ANo. 2,058,074). Typical examples of such anions are PF₆ ⁻, SbF₆ ⁻, BF₄⁻, and ClO₄ ⁻.

Preferred anions are those of, for example, sulfonic acids and acidsthat can be formed, possibly in situ, by interacting a Lewis acid suchas, for example, BF₃, AsF₅, SbF₅, PF₅, TaF₅ or NbF₅ with a Broenstedacid such as, for example, a hydrohalogenic acid, in particular HF,fluosulfonic acid, phosphoric acid or sulfuric acid. Specified examplesof acids of the latter type are fluosilicic acid, HBF₄, HPF₆ and HSbF₆.Examples of usable sulfonic acids are fluosulfonic acid andchlorosulfonic acid and the hereinafter specified sulfonic acids.

A preferred group of anions are anions of acids having the generalformula ##STR1## in which X represents sulfur or chlorine and, if X ischlorine, R⁷ represents oxygen and, if X is sulfur, R⁷ represents an OHgroup or an optionally substituted hydrocarbon group.

When the hereinbefore stated acids are used in the process according tothe invention, the anions of the acids can be considered to benon-coordinating. The anions are preferably used in the form of theacids themselves, but under certain conditions it is also possible touse them in the form of salts, e.g., AgBF₄, AgSBF₆ or Ag-p-tolunenesulfonate. The point is that it must be possible for the anion of theGroup VIII metal compound to be exchanged with the anion of the salt.

In the acids having the general formula I, the optionally substitutedhydrocarbon group represented by R⁷ is preferably an alkyl, aryl,aralkyl or alkaryl group having 1-30, in particular 1-14, carbon atoms.The hydrocarbon group may, for example, be substituted with the halogenatoms, in particular fluorine atoms. Examples of suitable acids of thegeneral formula I are perchloric acid, sulfuric acid,2-hydroxypropane-2-sulfonic acid, p-toluene sulfonic acid andtrifluoromethanesulfonic acid, the last two acids being the mostpreferred. The acid of the general formula I can also be an ionexchanger containing sulfonic acid groups, such as, for example,Amberlite 252 H. In that case, the hydrocarbon group R⁷ is a polymerichydrocarbon group substituted with sulfonic acid groups, for example apolystyrene group.

The anion of the acid with a pKa<2 is preferably present in the reactionmixture in a quantity of 0.01-150, in particular 0.1-100 and mostpreferably of all 1-50 equivalents per gram atom Group VIII metal. It isto be noted that the aforesaid pKa is measured in aqueous solution at18° C.

The alkenically unsaturated hydrocarbon will as a rule be an alkene orcycloalkene with 2-30, preferably 2-12 carbon atoms. Examples ofsuitable alkenes are propylene, butene-1, butene-2, isobutylene, theisomeric pentenes, hexenes, octenes and dodecenes, cyclo-octene andcyclododecene. Ethylene is most preferred. Examples of other alkenicallyunsaturated hydrocarbons are styrene, alpha-methylstyrene, and dialkenesin which the two unsaturated groups are not conjugated.

Of the palladium, nickel or cobalt compounds, the first are preferredand the process according to the invention is hereinafter described infurther detail in respect of palladium compounds. This may, however, notbe regarded as limiting; the use of cobalt or nickel compounds remainsequally possible.

Both homogeneous and heterogeneous palladium compounds can be used.Homogeneous systems are preferred. Suitable palladium compounds aresalts of palladium with, for example, nitric acid, sulfuric acid oralkane carboxylic acids having not more than 12 carbon atoms. Salts ofhydrohalogenic acids are theoretically also usable, but have thedrawback that the halogen ion may have a corrosive action. Palladiumcarboxylates are the catalyst compounds preferably used, in particularpalladium acetate. In addition, palladium acetylacetonate can also beused. Palladium on carbon and palladium bonded to an ion exchanger, forexample one containing sulfonic acid groups, are examples of suitableheterogeneous palladium compounds.

The quantity of palladium compound is not critical. Preferably,quantities between 10⁻⁸ and 10⁻¹ mol palladium compound per molhydrocarbon to be polymerized are used. The molar ratio of alkenicallyunsaturated hydrocarbon to CO will as a rule range from 5:95 to 95:5,preferably from 1:5 to 5:1.

Where, in the bidentate ligand, it is said that substituents offeringsteric hindrance should be absent, this means that no substituents maybe present that are able to hinder the formation of complex compoundshaving the general formula II ##STR2##

In that formula, Y represents a non-coordinating anion, while Pd²⁺ canalso be written as ##STR3## in which the ligands L₁ and L₂ are weaklycoordinated solvent ligands, e.g. acetonitril, methanol, acetone, oracetylacetone, or correspond with those employed in the palladiumcompounds described in the preceding paragraph.

In the aforesaid ligands, M is preferably phosphorus. Hydrocarbon groupsR¹, R², R³ and R⁴ will as a rule contain 2 to 18 carbon atoms,preferably 6 to 14 carbon atoms. Aryl groups are the most suitable, inparticular the phenyl group. Preferred bridging groups --R-- are thosehaving the formula (CR⁵ R⁶)_(n) in which R⁵ and R⁶ are hydrogen atoms orhydrocarbon groups offering no steric hindrance and n is a number of atleast two, most preferably 2, 3 or 4. Substituents R⁵ and R⁶ arepreferably hydrogen atoms. The bridging groups R may also make part of acyclic structure, e.g. an aromatic or cycloaliphatic group, the carbonto carbon bond or bonds in the bridge may be saturated or unsaturatedand in the bridge or in the cyclic or non-cyclic groups attached to thebridge one or more hetero atoms, e.g. sulfur, oxygen, iron or nitrogen,may have been substituted for carbon atoms, other than the two carbonatoms which must be present in the bridge linking both atoms M.

Examples of suitable bidentate ligands are

1,3-di(diphenylphosphine)propane,

1,4-di(diphenylphosphine)butane,

2,3-dimethyl-1,4-di(diphenylphosphine)butane,

1,5-di(methyl-phenyl-phosphine)pentane,

1,4-di(dicyclohexylphosphine)butane,

1,5-di(dinaphthylphosphine)pentane,

1,3-di(di-p-tolylphosphine)propane,

1,4-di(di-p-methoxyphenylphosphine)butane,

1,2-di(diphenylphosphine)ethene,

2,3-di(diphenylphosphine)butene-2,

1,3-di(diphenylphosphine)-2-oxapropane,

2-methyl,2-(methyldiphenylphosphine)-1,3-di(diphenylphosphine)propane,

O,O'-di(diphenylphosphine)biphenyl,

1,2-di(diphenylphosphine)benzene,

2,3-di(diphenylphosphine)naphthalene,

1,2-di(diphenylphosphine)cyclohexane,

2,2-dimethyl-4,5-di(diphenylphosphine)dioxolane and ##STR4##

The bidentate ligand can be used in quantities, relative to thepalladium compound, that can range within wide limits, e.g., from 0.1 to10 mol per mol palladium compound. Preferred quantities range from 0.33to 3 mol per mol. If cobalt or nickel compounds are used, the quantityused is generally somewhat higher, preferred quantities then rangingfrom 5 to 20 mol per mol Group VIII metal compound.

In addition to the bidentate ligand, one or more monodentate ligands canalso be used in the preparation of the catalysts in order to influencethe molecular weight of the polymer to be prepared. Suitable monodentateligands are in particular triarylphosphines, such as triphenylphosphineand trinaphthylphosphine. The use of an excess of monodentate ligand inrelation to the Group VIII metal compound is recommended. Preferredquantities range from 10:1 to 60:1 in relating to the Group VIII metalcompound.

The carbon monoxide can be used in pure form or diluted with an inertgas such as nitrogen, noble gases or carbon dioxide in the processaccording to the invention. The presence of more than 60%v hydrogen isgenerally undesirable because too great a reduction of the molecularweight of the desired polymer may then occur.

Polymerization according to the invention is preferably performed at atemperature between 20° and 200° C., in particular between 50° and 150°C. The total pressure ranges between preferably 1 and 100, in particular20 and 75, bar gauge.

Polymerization according to the invention can be performed batchwise,continuously or semi-continuously according to solution polymerizationor suspension polymerization methods. Use of a liquid diluent isgenerally desirable. Lower alcohols, ethers, glycols and glycoethershave proved suitable. The polymers obtained are genuine co-polymerswhich are generally characterized by the formula ##STR5## wherein m is arelatively small number, for example 1 to 6, A is the "monomer" unitwhich is converted into a saturated hydrocarbon group and n a number of2, 3 or more preferably more than 10, e.g., 3000, 6000.

Instead of one "monomer" A, there may also be two different "monomers",e.g., ethylene and styrene, ethylene and acrylic acid, ethylene andvinyl acetate, ethylene and butylene-1, propylene and methylmetacrylate, butene-1 and acrylic acid, etc. As terminal groups of thepolymer, the following groups, among others, can be obtained: --CH₂--CH₃, ##STR6## if CH₃ OH is used as diluent and ##STR7## if ethyleneglycol is used; ##STR8## if water is used and ##STR9## if carboxylicacids are used. The activity of the catalysts can be so high thatcatalyst residues need not be removed from the copolymer obtained. Thiseliminates the need to purify the copolymer and/or recover palladium,which signifies a major economic advantage.

The process according to the invention is hereinafter illustrated on thebasis of practical examples.

EXAMPLES

A magnetically stirred 250-ml autoclave was charged with 50 ml methanol,0.1 mmol palladium acetate, 0.15 mmol 1,3-di(diphenylphosphine)propaneand 2 mmol p-toluene sulfonic acid. The autoclave was flushed with CO,filled with ethylene at a pressure of 20 bar and CO at a pressure of 30bar, sealed and heated at a certain temperature for a cetain period oftime. On completion the polymer yield was determined and calculated ingrams polymer per gram palladium per hour. NMR analysis was alsoperformed to determine the terminal groups present and the meanmolecular weight. The results of this experiment (test 1) are stated inTable I.

For comparison, tests 1a and 1b were performed. In test 1a a catalyticsystem was used which was obtained by reacting 0.1 mmol palladiumacetate, 3 mmol triphenylphosphine (a monodentate ligand) and 2 mmolp-toluene sulfonic acid. The catalytic system of test 1b was obtained byreacting 0.1 mmol palladium acetate and 0.15 mmol1,3-di(diphenylphosphine)propane, but no p-toluene sulfonic acid.

For further comparison tests 1c and 1d were carried out. In tests 1c, asacid 2 mmol H₃ PO₄ were used instead of p-toluene sulfonic acid and intest 1d the acid was 2 mmol HCl.

In test 2, 1,4-di(diphenylphosphine)butane was used to prepare thecatalytic system instead of the propane derivate. Other differentconditions are stated in Table I, for the rest the conditions remainedunchanged in test 1.

In test 3 the same catalyst was used as in test 1. However, theautoclave was filled with CO at 30 bar, ethylene at 20 bar and hydrogenat 10 bar.

In test 4, test 1 was repeated using 50 ml diglyme instead of methanol.

In test 5, 2 mmol HBF₄ were used instead of p-toluene sulfonic acid.

In test 6, test 1 was repeated with 3 mmol triphenylphosphine alsopresent.

In test 7, the catalytic system of test 2 was used again with diethyleneglycol being used as reaction medium.

In test 8, the catalytic system of test 1 was used; the reaction mediumwas now 1,4-butanediol and the partial pressures amounted to 40 bar COand 10 bar ethylene.

In test 9, test 1 was repeated, except for the use of ethylene glycol asreaction medium, under the conditions stated in Table I.

In test 10, test 2 was repeated with ethylene glycol used as reactionmedium.

In tests 11-15, a complex was used that was obtained by first performingthe reaction PdCl₂ +AgBF₄ →PD(BF₄)₂ +AgCl and then reacting 0.5 mmol(Pd(BF₄)₂ with 0.5 mmol 1,3-di(diphenylphosphine)propane in acetonitrileas solvent. In tests 12 and 14 the complex was used without added acid,in tests 11, 13 and 15, 2 mmol HBF₄ were added to 0.1 mmol of thecomplex.

In tests 11 and 12, 50 ml methanol were used as reaction medium, in test13, 50 ml ethylene glycol and in tests 14 and 15, 50 ml diglyme. Partialpressures were 30 bar CO and 20 bar ethylene glycol in tests 11, 12 and13, and 20 bar CO, 20 bar ethylene and 20 bar hydrogen in tests 14 and15.

In test 16 the catalyst was obtained by reacting 0.12 mmol nickelacetate, 1.5 mmol 1,3-di(diphenylphosphine)propane and 2 mmol p-toluenesulfonic acid. The reaction medium during polymerization was 50 mlmethanol.

In test 17 the catalyst was obtained by reacting 0.12 mmol cobaltacetate, 1.5 mmol 1,4-di(diphenylphosphine)butane and 2 mmol p-toluenesulfonic acid. In this case too, 50 ml methanol were used as reactionmedium.

                  TABLE I                                                         ______________________________________                                         Test                                                                               T(°C.)                                                                         (hours)Time                                                                            g/g/hYield                                                                            ##STR10##                                                                             groups (%)Terminal                     ______________________________________                                         1   135     0.25     3000    2600    A(71), B(29)                             1a  135     0.25     --*     --      --                                       1b  135     15       --*     --      --                                       1c  135     5         10     --      --                                       1d  135     5         10     --      --                                       2   110     0.16     4800    1800    A(49), B(51)                             3   135     0.16     6000    1499    A(92), B(8)                              4   135     1.5       700    2000    A(100)                                   5   110     0.25     5000    --      --                                       6   135     1        1000     250    A(50), B(50)                             7   120     5        1200    2000    A(100), (i)                              8   115     5         650    1500    A(99), (ii)                              9   115     5         500    2150    A(88), C(12)                            10    80     5         200    15000   A(100)                                  11   100     5         600    7500    A(62), B(38)                            12   100     5         300     860    A(56), B(44)                            13   110     5         250    3050    A(75), C(25)                            14    85     5         100    30000   A(100)                                  15    70     5         200    30000   A(100)                                  16   135     5         100**   150    A(83), B(17)                            17   135     5         60***  --      --                                      ______________________________________                                         ##STR11##                                                                     ##STR12##                                                                     ##STR13##                                                                     (i) also present in chain: groups                                             ##STR14##                                                                     (ii) also present in chain: groups                                            ##STR15##                                                                     ##STR16##                                                                     **g/g Ni/h                                                                    ***g/g Co/h                                                              

EXAMPLE II

Palladiumchloride and the silver salt of p.toluenesulphonic acid werereacted in acetonitrile solvent to form a complex compound correspondingwith the formula Pd(CH₃ --CN)₂ (O₃ S--C₆ H₄ --CH₃)₂.

0.1 mmol of this complex were combined with various bidentate phosphineligands, each time employing 0.1 mmol phosphine per 0.1 mmol ofbidentate ligand.

Ethylene and CO were copolymerized at 84° C., 45 bar total pressure anda palladium concentration of 0.1 milliat. in 150 ml methanol. Thevolumetric feed ratio of CO to ethylene was 1:1, this corresponds with agas cap ratio of 2:1 (CO:C₂ H₄).

The ligands employed were:

run 18: 1,2-di(diphenylphosphine)ethane

run 19: 1,3-di(diphenylphosphine)propane

run 20: 1,4-di(diphenylphosphine)butane

run 21: 1,2-di(diphenylphosphine)benzene

run 22:2-methyl,2-(methyldiphenylphosphine)-1,3-di(diphenylphosphine)propane.

The latter compound, i.e. CH₃ --C--(CH₂ --P(C₆ H₅)₂)₃, although beingtrifunctional, is nevertheless considered a bidentate ligand in theterms of this invention since only two of the three phosphorus atoms cancoordinate with the palladium atom in the complex compound.

The results of the polymerization runs are illustrated in Table II.

                  TABLE II                                                        ______________________________________                                        Run         Time (hours)                                                                             Yield g/g/h                                            ______________________________________                                        18          3.1        106                                                    19          1.1        1657                                                   20          3.0        570                                                    21          1.75       544                                                    22          3.0        2412                                                   ______________________________________                                    

What is claimed is:
 1. In a process for the preparation of a polyketoneby contacting a mixture of CO and an alkenically unsaturated hydrocarbonwith a catalyst the improvement which comprises contacting the CO andthe alkenically unsaturated hydrocarbon in the presence of a catalystcomprising a Group VIII metal complex containing bidentate ligands, theGroup VIII metal selected from the group consisting of palladium,cobalt, and nickel, the ligands comprising hydrocarbon groups bonded toa Group Va element selected from the group consisting of phosphorus,arsenic, and antimony, wherein the catalyst is a complex compound thatis obtained by reacting (1) a palladium, cobalt or nickel compound, (2)a bidentate ligand of the general formula ##STR17## in which M is aGroup Va element selected from the group consisting of phosphorus,arsenic, and antimony, R¹, R², R³, and R⁴ are identical or differenthydrocarbon groups, R represents a divalent organic bridging grouphaving at least two carbon atoms in the bridge, wherein the carbon atomsof the bridging group R do not contain substituents that wouldsterically hinder formation of the complex compound, and (3) an anion ofan acid with a pKa of less than 2, provided said acid is neither ahydrohalogenic acid nor carboxylic acid.
 2. The process according toclaim 1 wherein the anion is a non-coordinating anion.
 3. The processaccording to claim 2 wherein the anion is an anion of sulfuric acid oran acid formed by interacting a Lewis acid with a Broensted acid.
 4. Theprocess according to claim 1 wherein the anion is an anion of an acidhaving the general formula ##STR18## in which X represents sulfur orchlorine and, when X is chlorine, R⁷ represents oxygen and, when X issulfur, R⁷ represents an OH group or hydrocarbon group.
 5. The processaccording to claim 4 wherein X is sulfur and the hydrocarbon group R⁷ isan alkyl, aryl, aralkyl or alkaryl group having 1-30 carbon atoms. 6.The process according to claim 4 wherein the anion is an anion ofp-toluene sulfonic acid of trifluromethanesulfonic acid.
 7. The processaccording to claim 1 wherein the hydrocarbon groups R¹, R², R³ and R⁴are aryl groups having 6-14 carbon atoms.
 8. The process according toclaim 7 wherein the aryl groups are phenyl groups.
 9. The processaccording to claim 1 wherein the mol ratio of bidentate ligand to GroupVIII metal compound selected from the group consisting of compounds ofpalladium, nickel and cobalt is 0.1:10 mol bidentate ligand per molmetal compound.
 10. The process according to claim 1 wherein (1) is apalladium compound.
 11. The process according to claim 1 wherein thebidentate ligand is a phosphine.
 12. The process according to claim 1 inwhich group --R-- represents a group --(CR⁵ R⁶)_(n) -- in which n is anumber of at least 2 and R⁵ and R⁶ are hydrogen atoms or hydrocarbongroups that will not sterically hinder formation of the complexcompound.
 13. The process according to claim 1 wherein the alkenicallyunsaturated hydrocarbon is ethylene.